And sitting next to an open window is not necessarily the best place on the bus.
With regard to airborne germs, good ventilation "may dilute it a little," says Markel. However, there are no conclusive studies that directly suggest the window seat on the bus is a flu-free sanctuary.
Several studies have shown that viruses tend to be transmitted from the hands to mouth, to eyes and other body parts that are touched. According to Gerba, adults touch themselves with their hands about 18 times per hour -- which makes frequent hand-washing all the more important.
"The best thing you can do is hand hygiene," said Gerba. "The rails and poles you hold on to -- that tends to be germy."
If a sink is not within reach, carrying around an antimicrobial hand gel that is alcohol-based can be a good alternative to soap and water.
"I would emphasize using any antimicrobial hand gel -- I take that on airlines," recommends Dr. Mark Dykewicz, professor of internal medicine at St. Louis University School of Medicine.
Other measures normally associated with cold and flu prevention apply on public transit as well. This includes eating well and exercising, general good health practices and getting the flu shot every year.
"In general, if people would go and get their flu shots, that might help stop some of the transmission," says Dr. Phyllis Kozarsky, expert consultant in the Division of Global Migration and Quarantine at the U.S. Centers for Disease Control and Prevention.
And if you have the flu, Kozarsky says, it behooves you to respect your fellow travelers by simply staying home.
"Unfortunately, we're often in crowded places -- crowded shopping malls before Christmas, schools, not just on public transportation." says Kozarsky. "It's important to be courteous. When you yourself have a fever or cold, it's best to stay at home. [Also], keep your kids at home if they're sick."
Usually during the cold winter months, we don heavy coats, scarves and gloves to shield us from the blistering weather. But wearing these items while traveling does not necessarily keep us safe from cold and flu viruses. Kozarsky says that what you do with gloves afterward is key.
"You're sitting on the bus, touching the handles, the bars, touching and rubbing your eyes and your face with your gloves," says Kozarsky, adding that in most cases, people are not washing or disposing of their gloves after wearing them.
"They give people an artificial sense that they're helping themselves," Kozarsky remarks. "Hand-washing is more preferable."
Scarves that cover your face also do not act similarly to surgical masks proven to effectively keep germs at bay. Although it may seem like they act as barriers, the microbes can pass through the holes within the knit scarf or fabric.
"I don't know any data that suggest scarves are protective," Kozarsky acknowledges.
If, however, you really want to ward yourself from the cold and flu effectively, you can emulate what laboratory scientists wear as protection -- although you may get funny looks from other passengers.
"The first lines of defense -- the air and touch -- are the backbone of public health prevention," says Dr. Neil Kao, chair of the Allergic Diseases and Asthma Center in Greenville, S.C. "If you get a mask, wear gloves, you have a 99 percent chance of preventing yourself from getting the cold or flu."